Engine air supply control method which is intended, for example, for the control of a turbocharged engine

Abstract

An engine air supply control method relating to a turbocharged engine including an intake manifold ( 20 ) which is disposed downstream of the compressor of the turbocharger ( 14 ) and an exhaust manifold ( 22 ) which is disposed upstream of the turbine of the turbocharger ( 14 ). The method includes determining the mass air flow supplying the engine and/or the pressure in the intake manifold ( 20 ) and the temperature in the exhaust manifold. The pressure in the exhaust manifold ( 22 ) is determined as a function of the pressure in the intake manifold ( 20 ), the engine speed, the temperatures in the cylinders ( 4 ) and in the exhaust manifold ( 22 ), the pressure in the intake manifold ( 20 ) being optionally determined from the mass air flow. Inversely, the pressure in the intake manifold.

1. An air supply control method for a turbocharged engine having an intake manifold ( 20 ) downstream of a compressor of a turbocharger ( 14 ) and an exhaust manifold ( 22 ) upstream of a turbine of the turbocharger ( 14 ), comprising:
 determining a mass air flow supplied to the engine and/or a pressure in the intake manifold ( 20 ), together with a temperature in the exhaust manifold, wherein a pressure in the exhaust manifold ( 22 ) is determined as a function of the pressure in the intake manifold ( 20 ), an engine speed, and temperatures in cylinders ( 4 ) and in the exhaust manifold ( 22 ), 
 wherein a correction factor dependent on the ambient surrounding pressure is provided, and 
 wherein the pressure in the exhaust manifold ( 22 ) P exh  is calculated by a formula:
     P   exh   =[A ( T   c )* MAP−B ( N, AMP, T   exh )]/ C ( T   exh ), 
 where A, B and C are predetermined functions, T c  is the temperature in the cylinders, MAP is the pressure in the intake manifold, N is the engine speed, AMP is the ambient pressure and T exh  is the temperature of burnt gases in the exhaust manifold. 
 
 
   
   
     2. The control method as claimed in  claim 1 , wherein the air flow supplied to the engine is regulated by a throttle valve ( 18 ), and in that, when this throttle valve ( 18 ) is near its closed position within predetermined limits during a specified time interval, an ambient external pressure AMP is calculated on a basis of the exhaust pressure as a function of the engine speed. 
   
   
     3. An air supply control method for a turbocharged engine having an intake manifold ( 20 ) downstream of a compressor of a turbocharger ( 14 ) and an exhaust manifold ( 22 ) upstream of a turbine of the turbocharger ( 14 ), comprising:
 determining a mass air flow supplied to an engine and/or a pressure in an intake manifold ( 20 ), together with a temperature in the exhaust manifold ( 22 ), wherein a pressure in the exhaust manifold ( 22 ) is measured by a sensor, and in that the pressure in the intake manifold ( 20 ) is determined on the basis of an exhaust pressure measured as a function of an engine speed and temperatures in the cylinders ( 4 ) and in the exhaust manifold ( 22 ), 
 wherein a correction factor dependent on the ambient surrounding pressure is provided, and 
 wherein the pressure in the intake manifold MAP is calculated by a formula:
     MAP=[F ( N, T   exh )* P   exh   +G ( N, AMP, T   exh )]/[ H ( N, T   c )], 
 where F, G and H are predetermined functions, T c  is the temperature in the cylinders, P exh  is the pressure in the exhaust manifold, N is the engine speed, AMP is the ambient pressure and T exh  is the temperature of burnt gases in the exhaust manifold. 
 
 
   
   
     4. The control method as claimed in  claim 1 , wherein the temperature in the exhaust manifold ( 22 ) is determined on the basis of modeling. 
   
   
     5. The control method as claimed in  claim 1 , wherein the air flow supplied to the engine is regulated by a throttle valve ( 18 ) , and in that, when this throttle valve ( 18 ) is near its closed position within predetermined limits during a specified time interval, an ambient external pressure AMP is calculated on a basis of the exhaust pressure as a function of the engine speed. 
   
   
     6. The control method as claimed in  claim 1 , wherein the air flow supplied to the engine is regulated by a throttle valve ( 18 ), and in that, when this throttle valve ( 18 ) is near its closed position within predetermined limits during a specified time interval, the ambient external pressure AMP is calculated on a basis of the exhaust pressure as a function of the engine speed. 
   
   
     7. The control method as claimed in  claim 1 , wherein an air intake ( 10 ) and a mass air flow meter ( 12 ) are upstream of the turbocharger ( 14 ). 
   
   
     8. The control method as claimed in  claim 1 , wherein an intercooler ( 16 ) is downstream of the turbocharger ( 14 ). 
   
   
     9. The control method as claimed in  claim 3 , wherein an air intake ( 10 ) and a mass air flow meter ( 12 ) are upstream of the turbocharger ( 14 ). 
   
   
     10. The control method as claimed in  claim 3 , wherein an intercooler ( 16 ) is downstream of the turbocharger ( 14 ). 
   
   
     11. The control method as claimed in  claim 1 , wherein the air flow supplied to the engine is regulated by a mechanically or electrically controlled throttle valve ( 18 ), and when the throttle valve ( 18 ) is electrically controlled, an angle of opening of the throttle valve and opening of a turbocharger discharge valve ( 14 ) are controlled simultaneously. 
   
   
     12. The control method as claimed in  claim 3 , wherein the air flow supplied to the engine is regulated by a mechanically or electrically controlled throttle valve ( 18 ), and when the throttle valve ( 18 ) is electrically controlled, an angle of opening of the throttle valve and opening of a turbocharger discharge valve ( 14 ) are controlled simultaneously. 
   
   
     13. The control method as claimed in  claim 1 , wherein a correlation between a measured value and the determined pressure in the exhaust manifold ( 22 ) is greater than 0.9. 
   
   
     14. The control method as claimed in  claim 3 , wherein a correlation between a measured value and the determined pressure in the intake manifold ( 20 ) is greater than 0.9.